2011 has been a very up-and-down year for Waterloo, Ontario’s Research in Motion. Apart from the massive worldwide service failure that crippled BlackBerry email delivery and BBM, the BlackBerry PlayBook has never quite lived up to its tablet potential. Recent temporary price cuts helped shift truckloads of stale stock, but now RIM appears to be faltering again.

The increased sales should have done loads of good for the PlayBook, but the fact is that until the PlayBook OS 2.0 update gets pushed to all these new users it’s still missing some cornerstones of the BlackBerry experience: email, contacts, calendar apps and BBM. At least we thought BBM was coming.

The BBM icon has been seen in loads of pre-release screenshots of PlayBook OS 2.0, but now RIM has officially announced that it is shipping the update without BBM. The company has decided to delay the release of BBM until an unnamed future update. You can, of course, still pair the PlayBook with a BlackBerry phone and use the BBM Bridge app — but that’s not quite the same thing as a full-on native app.

Couple news of this delay with the arrival of iMessage in iOS 5 and the speedy new iPhone 4S, and one more bit of news that hit the headlines isn’t at all shocking: gadget trade-in site Gazelle has announced that BlackBerry swaps are up more than 80% in the wake of the iPhone 4S launch.

So now it’s going to be four more months until the missing native apps arrive on the PlayBook — and even then it’s still going to lack BBM. It’s another misstep by RIM, and one that isn’t going to help it compete in the tablet market once the iPad 3 and Windows 8 slates start arriving on retail shelves early next year.